There has been conventionally known a linear guide apparatus using a rolling motion of balls, including a guide rail formed with a rolling groove for the balls in a longitudinal direction thereof, and a slider mounted to the guide rail via a large number of balls, and including an endless circulation path for the balls, in which the balls are allowed to circulate in the endless circulation path, and the slider freely reciprocates along the guide rail. Guide rails and sliders of various structures depending on use purposes, applied loads, mounting spaces, and the like, are proposed, and linear guide apparatuses employing such guide rails and sliders are actually on the market. Of those, as a linear guide apparatus which is preferably used for a light-load purpose, applicable to a narrow mounting space, and low in cost, there is known a thin slide unit in which a plurality of metal plates are connected to thereby construct a slider (refer to Non-patent Document 1).
The slide unit includes a guide rail formed into a channel shape having a guide path defined by a pair of side walls, and a slider equipped with a ball carriage moving in the guide path of the guide rail. An inner side surface of each of the side walls of the guide rail is formed with a ball rolling groove. Balls held by the ball carriage are allowed to roll in the ball rolling groove, whereby the slider moves along the guide rail. The slider fixes the base plate to the ball carriage, and a delivery target object is fixed to the base plate. As shown in FIG. 7, the ball carriage includes two ball plates 100, 100, and a guide plate 101 interveningly mounted between the ball plates 100, in which the two ball plates 100, 100 have identical shapes, and face each other thereby being connected. In each of the ball plates 100, there are formed track-like ball grooves 102, and the ball plates 100 are combined so as to face each other, whereby endless circulation paths in which balls 103 circulates are formed.
In the case of combining the two ball plates 100, a load opening portion from which spherical surfaces of the balls 103 in each endless circulation path is formed. The balls 103 come into contact with the ball rolling surface of the guide rail via the load opening portion. Incidentally, the guide plate 101 sandwiched between the two ball plates 100 includes steeple-like guide claws 104 located both ends of the load opening portion in the longitudinal direction. When the ball 103 having rolled in the ball rolling groove of the guide rail reaches an end portion of the load opening portion, the balls 103 climb on the guide claw 104 to be apart from the ball rolling groove, and accommodated in the endless circulation path. Further, when the balls 103 having circulated in the endless circulation path reach the load opening portion, the ball 103 are delivered into the ball rolling groove of the guide rail along the guide claw 104.
In order to suppress production cost, each of the guide rail and the slider of the slide unit is mainly formed by plastic forming of a metal plate. For example, the guide rail is formed as follows. That is, a band-like metal plate is subjected to roll forming processing, so the side walls are bent and raised to thereby form the ball rolling groove, and finally the whole is cut into a predetermined length. Further, each ball plate constructing the ball carriage is formed as follows. That is, a band-like metal plate is subjected to drawing processing at a predetermined interval to thereby form the ball groove, and then the metal plate is cut at a position where the metal plate is slightly overlapped with the ball groove. Thus, the ball plate having a predetermined shape is completed.
Non-patent Document 1: THK Co., Ltd., Linear Motion System General Catalogue No. 401, p. n-3, “Slide Pack FBW.”